Gas turbine engines operate at high rotational velocities in normal operation, typically at tens of thousands of revolutions per minute (RPM). Operation at such high rotational velocities creates significant centrifugal force on the rotational members of such gas turbine engines, which force increases as the square of the rotational velocity. Therefore, to avoid catastrophic breakdown, a gas turbine engine should not ordinarily operate above its normal rotational velocity.
Consequently, a gas turbine engine may have an overspeed protection system that monitors overspeed conditions and shuts down the engine upon sensing such conditions. Typically, modern overspeed protection systems are microprocessor based and rely on appropriate software for their operation. Of course, the operational reliability of such systems is dependent upon the reliability of such software and the data storage equipment that stores and reads it. In some critical applications, dependence on such software and its associated data storage equipment is unsatisfactory or excessively expensive due to regulatory certification costs.